Re: Traits and Properties

2010/12/16 Stefan Marr <php@stefan-marr.de>: > Hi: > > From my point of view the right thing to do with regard to properties is defined in the test > cases below. > > The rational behind providing this semantics is based on the fact that PHP allows to define > properties dynamically anyway, so there is no way around properties. > However, there should be a way that a developer can notice that the code might not behave as > expected in the composed class. > > It is true that behavior needs state to operate on, however, accessors are a common pattern and > fully supported by traits. Furthermore, traits are not supposed to replace classes, and when a trait > does more than just providing code that is to be easily reused, then the designed should ask the > question whether that is not actually a class, which then provides the necessary guarantees to > enforce the invariances the code expects. > > Thus, I would like to keep traits as a lightweight concept for code reuse.. > > Best regards > Stefan > > --TEST-- > Conflicting properties should result in a notice. > Property use is discorage for traits that are supposed to enable maintainable > code reuse. Accessor methods are the language supported idiom for this. > --FILE-- > <?php > error_reporting(E_ALL); > > trait THello1 { >  public $foo; > } > > trait THello2 { >  private $foo; > } > > class TraitsTest { >        use THello1; >        use THello2; > } > > var_dump(property_exists('TraitsTest', 'foo')); > ?> > --EXPECTF-- > Notice: Trait THello1 and THello2 define the same property in the composition of TraitsTest. > This might be incompatible, to improve maintainability consider using accessor methods instead. > Class was composed in %s on line %d. In this test, you might want to display some text before the var_dump() (or alternatively to hardcode the line number on last line) to ensure it is the property_exists() function call or the class definition which would create such a notice. Regards, Patrick -- Patrick Allaert --- http://code.google.com/p/peclapm/ - Alternative PHP Monitor